It is known in the art that illuminated display systems, such as those found in receivers, compact disc players, and heating, ventilation, and air conditioning (HVAC) controllers, include a back-lit display panel. Typically, it has been common practice to locate light pipes between a printed circuit board and the display panel to direct light from a light source to a portion of the display panel for controlled illumination. However, because this location of the light pipe is typically shared by other electrical components and mechanical structures (i.e. button bodies, potentiometers, plastic ribs, LCD displays, etc.), the design of the light pipe may become complex, which may affect the efficiency of the lighting system.
Accordingly, a final design of the light pipe has often included complex structures that weave between the electrical components and mechanical structure. Once light is provided to an entrance port of the light pipe, gradual changes in direction of light propagation by means of total internal reflection on non-parallel light pipe walls tend to introduce losses as collimation decreases. Losses in collimation also increase the difficulty in directing light exiting the light pipe to the specific areas of the display panel.
The complexity of such light pipe designs makes computer simulation difficult and time consuming, which lends to prevention of design optimization by means of iterative prototyping and expensive design cycles drawn out with proof of concept often being delayed until injection molded light pipe prototypes can be produced. As such, a need exists for improving the collimation effects and efficiency of light pipes applied in an illuminated display system.